A compact and thin small-size image pickup apparatus using a solid state image pickup device, such as a CCD type image sensor and a CMOS type image sensor, has come to be mounted on a portable terminal, which is a compact and thin electronic device, such as a mobile phone and PDA (Personal Digital Assistant). Thereby, a mutual transmission of not only voice information but also image information to a remote place has become possible. With such small-size image pickup apparatus, there is a strong demand for both miniaturization and high definition, which realizes such image quality that user expect.
The small-size image pickup apparatus is mainly composed of a solid state image pickup device and an imaging lens. Although a solid state image pickup device the solid state image pickup device that having approximately five million pixels is already in the market to realize high definition, it has typically a comparatively large sensor size because it is used for a digital camera. However, recently, a pixel number has been increased due to the improvement in production technology, and a satisfactorily miniaturized solid state image pickup device having a large number of pixels has been developed. Therefore, the solid state image pickup device can be applied to the small-size image pickup apparatus.
On the other hand, as disclosed in U.S. Pat. No. 6,795,253, there has appeared a lens whose aberration is improved in response to increase in definition of this image pickup device.
Incidentally, in the case where such lens as disclosed in U.S. Pat. No. 6,795,253 is employed in a small-size image pickup apparatus of high definition, it should be further considered that there is a demand for high resolution. Here, for example, the aberration caused by an optical axis shift between individual lenses can be considered as a factor that affects resolution. However, in this case, since a further reduction of the manufacture error causes the manufacturing cost to increase, the optical axis shift may be reduced by aligning the individual lens. However, in the case of the small-size image pickup apparatus, whole alignment mechanism cannot be incorporated in the lens for the reasons: there is a limitation of space, and the alignment needs to be efficiently performed in order to improve the productivity for cost reduction.